Visual guidance using ultrasound images has been successfully used for inserting core biopsy needles into tissue to procure tissue samples from a living body, resulting in high rates of sensitivity of tissue diagnosis. Accurate positioning of a biopsy needle by ultrasound guidance can be facilitated by providing a set of numerical positioning data for the biopsy needle such as an insertion length of the needle to reach an object from a skin and an insertion angle between a longitudinal axis of the needle and a horizontal axis of an ultrasound transducer visualizing the tissue object. Accuracy in positioning increases further by visualizing a linear alignment between a point of a contact portion of a transducer and a center of a tissue object and by reversibly adjusting an insertion angle based on position changes in the point of the contact portion of the transducer relative to the center of the tissue object.
Accuracy in positioning also depends on hand-eye coordination of an operator who handles and controls the visual guidance apparatus. Most commonly, the hand-eye coordination relies on a dominant hand and a three-dimensional view acquiesced by both eyes. Single-hand operation using a dominant hand tends to be more accurate in navigating structures than double-hand operation except for using the other non-dominant hand for stabilizing an object that is a target of the operation by the dominant hand. One way to increase the accuracy in positioning a biopsy needle by a visual guidance apparatus is to free the non-dominant hand for the most of a procedure except for holding steady either the apparatus or a target tissue region. It requires the dominant hand to take care of the most of the procedure, which could be achieved if the majority of operations of the apparatus are automated and controllable by one hand. In particular, the visual alignment and the adjustment of an insertion angle, which are two most important movements of the visual guidance apparatus, should be made controllable and reliably reproducible by one hand.